Leonid MAC is NASA's first Astrobiology mission. Leonid MAC, a series of 5 missions that took flight in aircraft during the years 1998, 1999, 2000, 2001 and 2002. Its mission is to learn how extraterrestrial materials may have been brought to Earth at the time of the origin of life. In addition, the interaction of meteoroids with the atmosphere generates molecules that may have played a role in the origin of life on Earth.

The 1999 and 2001 Leonid MAC missions gathered a bounty of scientific data. Rates increased to 4,000 meteors per hour in 1999 and 1,300 per hour in 2001.